Insurgents have breached Syria’s largest city and clashed with government forces for the first time since 2016.

The fighting is a significant escalation since rebels launched a surprise offensive earlier this week, seizing towns and villages as they cut a path toward Syria’s second-largest city.

Thousands of insurgents continued their advance toward Aleppo city in Syria on Friday, seizing several towns and villages along the way. The offensive comes as Iran-linked groups, who have backed Syrian government forces since 2015,